In recent years, the size of analysis devices of various fields has been reduced. For example, a smaller-sized crystal inspection device is strongly demanded for bedside diagnosis in which diagnosis is made near a patient. Smaller-sized analysis devices are also strongly demanded for analysis of environmental pollutants in the air, water, or soil because these devices are used outdoors for such analysis.
Microfluid devices attract attention because of their potential to fit such needs. The microfluid devices have a substrate, for example, with a hand-portable and easy-handling size. The substrate has a plurality of fine channels formed therein to transport a reagent, a diluting solution, an analyte, and the like. The substrate is optionally provided therein with parts connected to the fine microchannels such as a reagent storage unit, an analyte supply unit, a diluting solution storage unit, a reaction chamber and a mixing unit.
The size of the microfluid devices have been reduced, and their substrates commonly have a size with planar area of about 1000 cm2 or less, and a thickness of about 0.5 mm to 10 mm. Therefore, the diameter of the fine channels formed in the inside of the substrate is commonly as remarkably thin as about 5 μm to 1 mm. If the channels are flat, the diameter of the fine channels is defined as the narrower width in the cross-section of the flat channels.
Since the microfluid such as the analyte, the diluting solution, or the reagent is transported through such channels with a remarkably small diameter, the microfluid is further more susceptible to factors such as the surface tension of the fluid and the wettability of the wall surfaces of the fine channels, unlike in conventional circuits in which a usual liquid is transported. Accordingly, various parts of such microfluid devices have been studied in various ways.
A method for forming a micropump in a substrate of such a microfluid device has been studied. The micropump is a driving source for transporting a microfluid in such fine channels as described above, and is typically a remarkably small pump having a total volume of 1 cm3 or less. For example, Patent Document 1 discloses a micropump having a remarkably small diaphragm structure provided by the MEMS processing technology. Patent Document 2 discloses a micropump that intermittently transports a liquid by a minute piston. Patent Document 3 discloses a pump that transports a liquid by an electroosmotic flow generated on fine channels. Patent Document 4 discloses a micropump of a hydrogen pump with a solid electrolyte used therein.
Patent Document 5 discloses a micropump in which a micropump chamber provided in a substrate is filled with a material that generates a gas in response to heat or light. In this case, the gas is generated by supplying thermal energy to or irradiating with light the material that generates a gas in response to heat or light in the micropump chamber. The pressure of the generated gas allows a microfluid in fine channels to be transported. Patent Document 5 recites that the material that generates a gas in response to heat or light is a polyoxyalkylene resin whose oxygen content is 15 to 55% by weight.    Patent Document 1: JP-A 2001-132646    Patent Document 2: JP-A 2002-021715    Patent Document 3: JP-A 10-10088    Patent Document 4: U.S. Pat. No. 3,489,670    Patent Document 5: JP-A 2005-297102